Specimen holder for polishing machine



g- 2, 1966 D. e. ZIMMERMAN SPECIMEN HOLDER FOR POLISHING MACHINE FiledAug. 9, 1963 INVENTOR. DONALD G. ZIMMERMAN BY W0 fw/KMMJ, VJ4Q1M ATTYS.

United States Patent 3,263,375 SPECIMEN HOLDER FOR POLISHING MACHINEDonald G. Zimmerman, Park Ridge, 111., assignor to lrecision ScientificCompany, Chicago, 111., a corporation of Illinois Filed Aug. 9, 1963,Ser. No. 301,082 1 Claim. ((Il. 51-217) The present invention relates tospecimen holders and more particularly to a holder for mounting embeddedmetallurgical samples in an automatic polishing machine.

An automatic polishing machine for metallurgical samples is usuallydesigned to accommodate three or more samples embedded in circularmounts or carriers molded of plastic, which may be 1" or 1%" in diameterand from /z" to %1" thick. One design of specimen holder is in the formof a disc having windows or openings to receive the mounts and laterallygrooved for receiving a clamping band which clamps all of the mountssimultaneously in position. In another common type of specimen holder aslot is cut through the material surrounding each of the openings andindividual clamping screws are provided for pulling the material on thetwo sides of the hole together to secure the clamping action. Suchdevices are inherently limited in usefulness by reason of the fact thatthey can accommodate only one diameter of mount. Moreover, the variousclosely fitted surfaces provide cracks and crevices for lodgement of thegrit so that it is diflicult to flush the carrier free of one grade ofgrit before proceeding to a finer grade in the successive polishingsteps.

It is an object of the present invention to provide a new and improvedspecimen holder which is capable of accommodating mounts within a rangeof diameter so that one holder may suflice in place of the severalnormally required. It is another object to provide a specimen holder inwhich each of the mounts is securely clamped in position with only asingle set screw but which nevertheless insures automatic alinement ofthe mounts with respect to the holder body with no possibility ofdislodgemen-t or cocking. It is moreover an object of the presentinvention to provide a specimen holder for an automatic polishingmachine or the like which is of open construction, free of any closelyspaced, closely fitted, or parallel surfaces and which therefore makesit an easy matter to flush the holder and the mounts secured thereincompletely free of grit as required in the successive polishing steps.Finally it is an object of the present invention to provide a specimenholder which, in spite of the advantages which it offers, isnevertheless of simple and inherently inexpensive construction.

Other objects and advantages of the invention will become apparent uponreading the attached detailed description and upon reference to thedrawing in which:

FIGURE 1 is a plan view of a specimen holder constructed in accordancewith the present invention and showing specimen mounts clamped in place.

FIG. 2 is a section looking along the line 22 in FIG. 1.

While the invention has been described in connection with a preferredembodiment, it will be understood that I do not intend to limit theinvention to the exact form shown but intend to cover such modificationsand alternative constructions as may be included within the spirit andscope of the appended claim.

Turning now to the drawing there is shown a specimen holder of discshape having a fiat front surface or face 11 and a back surface 12parallel thereto with a circular periphery 13. In use the specimenholder is driven in a polishing machine (not shown) by means of afriction drive consisting of two idler wheels and one drive wheel,rotating in contact with the periphery of the holder.

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Mounting post 15, which may be press fitted in the holder body, is usedto mount weights which deter-mine the polishing pressure. Formed in theholder body are a plurality of openings or windows, in the presentinstance three in number as indicated at 16, 17, 18, and which aresymmetrically distributed about the In accordance with the presentinvention each of the windows extends to Within a short distance of theperiphery and provides a peripheral wall penetrated by a single setscrew, with each of the windows having intersecting walls symmetricallyarranged with respect to the clamping axis of the set screw so that linecontact is established with a circular mount at widely spaced,symmetrically located points when the set screw is tightened. Thus inthe case of the present device, and taking the window 16 asrepresentative, it will be noted that it extends to within a relativelyshort distance of the periphery 13 to define a peripheral wall section20. This wall has formed therein a tapped hole 2 1 into which is screweda set screw 22 defining a clamping axis 23. symmetrically arranged withrespect to the clamping axis are a pair of intersectingly arranged walls24, 25 which serve as clamping surfaces. Since the holder and mountspreferably have appreciable thickness as indicated at FIG. 2, parallellines of contact are established having appreciable length to insureaxial alinement. Preferably the clamping surfaces 24, 25 are straight orof only limited curvature bearing an average angle with respect to theclamping axis on the order of 45.

Consequently, when a disc shaped mount is inserted into the window andthe set screw 22 turned tight, the mount is limited to line, or nearline contact at the points of engagement indicated at 31, 32respectively. Such line contact acts to distribute the clamping pressureover the entire axial length of the mount while avoiding closely spacedor parallel surfaces which might serve to entrap grit. Thus the openings33, 34 which are defined on the opposite side of the mount while ofgenerally crescent shape are sufficiently open and sufiiciently blunt atthe ends so that a pressure stream of water may be directed through theassembled holder with assurance that all of the grit will be flushedaway at the end of each grinding step and when the grit size is changedto a finer grade.

The present hold-er construction while minimizing the area in contactwith the mount nevertheless serves to hold the mount securelyperpendicular to the face of the holder while preventing any tendencytoward cocking of the mount during the polishing operation even thoughrelatively light clamping pressures are applied at the set screw. Inshort, since the clamping surfaces 24, 25 are perpendicular to the faceof the holder, the widely spaced lines of contact 31, 32 with the mountare precisely parallel with One another which insures that the mountwill be clamped with its axis precisely parallel to the axis of theholder with-out any care or attention on the part of the operator.

It is one of the features of the present construction that it is capableof accommodating cylindrical mounts having a wide range of diameter. Inthe particular embodiment shown, the mount 35 in window 17 is ofstandard 1" diameter whereas the mount 36 in window 18 has a diameter of1%". It will be apparent that the holder may he modified to accommodatean even wider range of mount diameter simply by scaling it up in size.

Since the mount is of one piece construction, for example of castaluminum, it is inexpensive to manufacture and capable of constant useover a long period of time without wear or loss of accuracy.

I claim as my invention:

A specimen holder for a metallurgical specimen polishing machine or thelike for holding cylindrical specimen mounts which comprises a one.piece body of disc shape having a flat face and having a plurality ofwindows formed therein symmetrically distributed about the axis andextending to within a short distance of the periphery to defineindividual peripheral wall portions, a set screw penetrating each of theperipheral wall portions and oriented along a clamping axis, each ofsaid openings having intersectingly arranged clamping surfaces at arelatively Wide angle parallel to the holder axis and syrnmetricallyarranged with respect to the clamping axis, the disc having appreciablethickness so that, when a cylindrical mount is inserted into one of theWindows and the set screw turned tight, line contact is established attwo Widely spaced points on the periphery of the mount symmetricallyarranged with respect to the point of contact of the set screw, saidintersectingly arranged surfaces being 4 p'osite ends by accuratesurfaces on opposite sides of the mount so as to define a pair ofgenerally crescent-shaped openings on the opposite sides of the mountwhich are relatively wide and blunt ended to facilitate flushing of theholder and assembled mounts freeof one size of grit prior to use of gritof progressively finer grade.

References Cited by the Examiner UNITED STATES PATENTS 2,466,610 4/1949Newman 51-2l7 2,746,218 5/1956 Bowie et a1 51-237 2,842,906 7/ 1-958Carter et a1 51-131 substantially straight and connected at each oftheir op- 15 HAROLD D. WHITEHEAD', Primary Examiner.

